4.2 Structure of the Nuclear AtomMAIN

IDEAS1. Electrons2. Cathode

Ray3. Protons4. Neutrons5. Nucleus

KEY CONCEPTS1. What are the kinds

of subatomic particles?

2. How can you describe the structure of the nuclear atom?

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Electron Cloud

REGIONS

PARTICLES

Neutron

Nucleus

ProtonElectron

I. Subatomic ParticlesA. Protons (+), Electrons (-), Neutrons (0) B. Change to Dalton’s Theory = atoms are divisible!

1. In 1897 JJ Thomson (1856 – 1940) discovered that atoms contain tiny, negatively charged particles called electrons using the Cathode Ray Experiments.

Negatively Charged Beam

Positively charge plates

Watch what happens when the magnet is placed above and below the electron beam.

D. Robert Milikan (1868-1953) 1. U.S. Physicist 2. Experiments quantity of

chargea. Thomson’s ratios

calculates mass of electron (1916)

3. One unit of negative charge & 1/1840 the mass of a Hydrogen atom

Why a Hydrogen atom?

1. 1932 – Eugene Goldstein (1850 – 1930)

a. Evidence of positively charged particles using Cathode Ray = Protons

b. Mass 1840 X an electron

2. 1932 James Chadwick, English Physicist (1891 -1974) discovers the neutron.

a. No Chargeb. Mass nearly = to proton

How are the subatomic particles arranged?

1. 1911, Ernest Rutherford (1871 -1937) provided evidence that the atom is mostly empty space. He named, nucleus = small dense (+) charged center.

a. Gold Foil Experiment – Alpha particles passing through & deflected by gold foil

Dalton’s Model

“Solid Sphere”

Thomson’s Model

“Plum Pudding”

“Solar System”

Rutherford’s

Model

NUCLEAR ATOM – Protons & Nuetrons in the nucleus. Electrons take up most of the volume

ORANGE

CARD

GREEN CARD #

NOTES = NTEXTBOOK

= T w/ PAGE

#

MISSED GREEN

CARD #’s

% CORREC

T

15 = N3

Card Sort Activity

Top ½ IaN pg. 4INFERENCE REFERENCE